Coil holder



Feb. 24, 1959 A. s. wALLlN` 2,874,915

con. HOLDER Filed May 5. 1954' l s sheets-sheet 1 Feb. 24, 1959 A. s. WALLIN 2,874,916

con HOLDER Filed May 5, 1954 5 Sheets-Sheet 2 Feb- 24, 1959 4 A. s. WALLIN 2,874,916

COIL HOLDER Filed May 5. 1954 y 5 Sheets-Sheet 3 @ff/MT Salaam Feb. 24, 1959 A. s. WALUN 2,874,916

COIL HOLDER Filed May 5, 1954 5 Sheets-Sheet 4 104 Z0 iQ /r Vgl Ik A.-s. WALLIN Feb. 24, 1959 COIL HOLDER Filed May 5, 1954 5 Sheets-Sheet 5 United States Patent O 2,874,916 colL HOLDER Arthur S. Wallin, Chicago, Ill., assgnor to Hydrometals, Inc., Chicago, lll., a corporation of Illinois Application May 5, 1954, Serial No.` 427,714

10 Claims. (Cl. 242-7551) holder to different sizes of coils and for rotatably driving the coils.

A further object is the provision of control means for radially expanding and retracting the arms of such a mandrel, the movement of the arms being automatically terminated when they have been expanded into contact of a predetermined pressure with the internal surface of a coil or when they have been retracted into mutual engagement.

It is still another object of the invention to provide means for unwinding a coil of sheet material so as to maintain automatically looseness of the outermost layers of the coil, thereby permitting the sheet material to shift laterally as required for alinement with the take-up or utilizing device.

Additional objects and advantages will become apparent as the following description proceeds, taken 1 conjunction with the accompanying drawings, inwhich:

Figure 1 is a front elevation of a coil holder constructed in accordance `with a preferred embodiment of the in vention;

Fig. 2 is a left side elevation of the coil holder shownA in Fig. 1;

Fig. 3 is an enlarged fragmentary elevation, partially in section taken along the line 3-3 in Fig. l, illustrating details of a friction brake;

Fig. 4 is a fragmentary cross-sectional view of the ex panding mandrel shown in Fig. 1;

Figs. 5 and 6 are perspective views of two respective types of arms for the expanding mandrel;

Fig. 7 is a schematic circuit diagram of a novel electrical control for the power expansion and contraction for the mandrel shown in Fig. l;

Fig. 8 is a schematic representation, partially in elec` tric circuit diagram form, of a novel control for rotating the holder to unwind a coil thereon;

Fig, 9 is an end elevation of a coil holder having a modified embodiment of the expanding mandrel 'of the present invention;

Fig. 1 0 is a fragmentary plan view taken substantially along the line 10-10 in Fig. 9; and` Fig; 11 is a fragmentary cross section taken substantially along the line 11-11 in Fig. 9 illustrating further details of the mandrel shown therein.

Although the invention has been shown and is described in some detail with reference to particular ernbodiments, there is no intention to thereby limit it to such detail. On the contrary, the intention here is to overall alterations, modifications, and equivalents fall- ICC ing within the spirit and scope of the invention as defined by the appended claims.

The problem is posed in the coiling and uncoiling of4 sheet material, for example soft sheet metal, of providing a single coil holder which may effectively accommodate a wide variety of coils having different weights, widths, and internal diameters, as well as materials of different thicknesses and degrees of stiffness. In the` coiling of non-ferrous sheet metals or light gauge sheet steel, merely slipping a coil over an under-size supporting shaft is unsatisfactory. The lack of rigidity and the weight of the material soon results in the coil becoming egg-shaped in cross section, making it extremely diicult to wind or unwind. To prevent such distortion in shape, coils of such non-rigid sheet material must be formed to have relatively sr'nall inside diameters. Yet, the inside diameters must be capable of variation to meet consumer specifications.

' On the other hand, coils of heavier gauge, stiffer ma terial must have larger internal diameters to prevent a bending or setting of the innermost layers. The size and weight of such coils sometimes are radically greater than coils of softer, lighter ygauge non-ferrous sheet metals. t

The present coil holding arrangement is intended to satisfy the extreme requirements for the versatile handling of such different coils and to accommodate easily large, heavy coils through the provision of power means automatically controlled in a novel manner.

Referring now to the drawings, an exemplary coil holder embodying the features of the invention is shown in Fig.` 1. Briefly, the coil holder vincludes a support or frame 15 Vsuitably journaling a shaft 18 which carries on one end an `expanding mandrel 19 of unique and advantageous construction. For supporting a coil 20 of sheet material, the mandrel has a plurality of elongated axially extending arms 21 which are radially expandable and contractable in a manner to be more fully described,

The support 15 make take a variety of forms. It is here shown as having a bed 22 on four legs 24, the latter adapted by a base plate 25 to be bolted to the oor. The shaft 18 is preferably hollow and elevated above the bed, journaled in spaced pedestal bearings 26.` A guide plate 28 abuts the inner edge of the coil mounted on the mandrel arms and thusserves to keep the edge of the coil smooth during Winding. The mandrel arms 21 extend through a large central opening 29 in the guide plate, rotating freely in any of their radial positions. For adapting the guide plate 29 to abut coils of various widths, to thus position the coils axially along the arms, and for permitting retraction of the plate free of' the supported coil, it is mounted on the ends of a pair of rods 30 which are axially slidable in sleeves 31 bolted to the support legs 24. Axial positioning of the guide plate 28 is accomplished by turning a hand wheel 32 on the right end of a threaded shaft 34. This shaft is journaled for rotation and axial sliding in a bushing 35 carried by a strap 36 between the right legs (Fig. 1); and its threaded portion 34a is engaged with a tapped sleeve 38 on a strap 39 between the left legs. The left end of the shaft 34 has a collar 40 axially captive and rotatably disposed in a bushing 41 rigid on the lower edge of the guide plate 28.

For imposing a variable drag on the shaft 18 when operation of the coil holder requires, as hereinafter explained, a brake assembly 42 is provided which comprises a sleeve 44 fixed on the shaft 18 by set screws 4S and having a narrower, larger diameter portion 46 serving as a brake drum. A brake band 48 substantially surrounds the drum, being supported at the front by a U-shaped bracket 49 carried by a pin 50 in a standard 51 bolted to the` bed 22. At the rear, a tension device is attached to the opposite ends of the band. As here shown, this device isA supported on a second pstandard 52 and includes a pair of straps 54 fastened to the band 48 and extending for welded attachment to a lpair of plates 55 slidable on an upright bolt 56 and urged apart Vby compression springs- 58, 59 bearing against a flange 60v mounting the bolt 56. Tension' is applied to the band- 48 by pulling the plates 55 toward one another by means of a camming plate 61 pinned in a bracket 62 held captive on the upper end of the bolt by an adjustment nut 64. By moving a handle 65 on the camming plate 61 counterclockwise (Fig. 3) to push the top plate 55 downwardly, the brake is applied, whereas it is released in the position shown. Initial and final braking torques' may be set by adjusting the nut 56.

As' here shown, the expanding mandrel 19 is constructed ina manner to permit extensive radial adjustment of the arms 21, thereby accommodating a wide variety of coils having different internal diameters, weights, and widths. In accomplishing this objective, a universal machine type tool chuck, readily available commercially, is employed, the usual jaws of such chuckbeing removed and the special arms 21 mounted in lieu of such jaws. The chuck includes therein a mechanism for radially expanding and contracting the arms in unison, such mechanism being susceptible of power actuation.

As best shown in Figs. l, 2, and 4, the preferred form of chuck comprises a hollowk housing 79 having a collar 71 keyed as at 72 on the left end of the shaft 18. The outerwall of the housing 70 has a pluralityof radially extending slots receiving` radially slidable pads 74, there being three such pads in the present instance. For mounting the mandrel arms, the pads 74 are formed with a plurality of transverse keyw'ays 75 and a pair of spaced, tapped openings 76. In order that' the pads 74 may be adjusted radially in unison, the inner face of each is provided with spiral buttress' threads 78 which are engaged with mating threads on a scroll ring 79. The latter is bolted to a circular plate 8i) fast on the end of an actuator rod 81 which extends through and is rotatable relative to the hollow shaft 18. Support for the rod and plate is effected by a collar 82 journaled in the left half of the housing 70 (Fig. 4) by a ball bearing 84, and a thrust ball bearing 85 interposed between the opposite side of the plate 80 and the housing.

' During winding or unwinding of a coil 20 on the mandr'el arms 21, the shaft 18 and actuator rod 81 rotate together. But for quickly adjusting the radial positions of the arms 21, the shaft 18 may be restrained, for example, by the brake assembly 42, and the rod 81 and plate 80 turned with respect to the housing 70 in the bearings 84 and 85. This turns the scroll ring 79 and effects a threaded movement of the pads 74 radially inward or outward. Such adjustment may be accomplished to place the mandrel arms 21 in any of a wide range of radial positions, and it may be carried out in an instant.

For mounting the three arms 21, their end bases 85 have a set of projecting keys 86 inser'table into the keyways 75 of the pads 74, and openings 88 for receiving securing bolts 89 inserted therethrough for threaded engagement with the tapped holes 76.

The arms 21 extend at right angles from the radially innermost sides of their bases 85, being of considerable length to accommodate coils of relatively great width. It is to be noted that since the arms are not fettered by an adjusting mechanism interposed between them, they may be radially retracted to lie in a circle of very small diameter. They are thus easily inserted into coils having relatively small internal diameters.

The arms are curved on their outer sides for engagement with the circular surface of the coil opening. Manifes'tly,.a given curvature of arrn surfaces will not smoothly match all the internal surfaces of coils having a wide range of internal diameters. However, such perfect matching is not `necessary tothe secure support of the coils, and with three such arms extending at 120 degree intervals', the desired support is obtained by a slight radial' stretching or bearing pressure. In the form shown in Vig'. i5', the arms 21 have a relatively sharply curved surface 90 to form a small composite cylinder when retracted into mutual abutment. This is ideal for a range of smaller coil internal diameters. In the second form illustrated by Fig. 6, the arms 21a have outer surfaces 90a of less curvature, i. e., a greater radius of curvature, matching to a greater degree the inner surfaces of larger coil openings. Otherwise, the two forms are the same and may be used interchangeably for coils of different size groupsQilther form, however, will serve satisfactorily for coils having central openings varying between the limits of adjustment accorded by the chuck.

In accordance with an important feature of the invention, power means are provided for driving the adjusting mechanism of the mandrel 19, such power means being controlled in a manner so as to be automatically deenergized whenever the radial movement of the mandrel arms 21 is resisted by a predetermined force. Thus, whenever the pads 74 reach their inner or outer limits of travel relative to the threads on the scroll ring 79, or whenever the arms 21 are expanded into firm engagement with the inner surface of a coil, thereby setting up a resistance to further radial movement of the arms, the movement is automatically terminated. The operator need not worry'about' vstopping radial movement of the arms before destructive stresses are created; yet he may be sure that each coil will be securely engaged by the arms.

The exemplary power means here shown for driving the mandrel adjusting mechanism, include a reversible motor suitably connected with the actuator rod 81. As shown in Eig. 1, the motor 95 is mounted at the right end ofthe support 15, its shaft being connected with the right end of the rod 81 which projects from within the hollow shaft 18. With the braking device 42set to hold the shaft` 18 stationary, energization of the motor 95 so that it rotates in one direction or the other thus correspondingly rotates the scroll ring 79 to adjust the pads 74 and the mandrel arms 21 radially inward or outward.

Forlthe automatic deenergization of the motor 95, a control circuit exemplified by that illustrated in Fig. 7 is employed. As there shown, the motor 95 is of the three-'phase induction type and is reversibly energized trompa three-phase voltage source through contacts Re1 3 and Rc1 g of relays having respective coils Re and Re, Closing ofthe contacts Re1 3 energizes the motor 95 in a direction to expand the mandrel arms, while closure of the contacts Rc1 3 causes the motor to rotate in the opposite direction to contract the mandrel arms. Energiz'ation of the controlling coils Re and Rc is elected through a circuit fed from two of the voltage supply lines through suitable protective or overload devices O1 and- O2.

vTo initiate expanding movement of the mandrel arms, a double-contact push button switch S1 is momentarily closed, completing a circuit through the overload device O1, the coil Re, contacts SRL of the push button switch, a normally closed push button stop switch S2, and the second overload device O2. This closes the contacts R1 3 and energizes the motor 95. At the same time, however, normally open contacts R84, controlled by the coil Re, are closed to complete a seal-in circuit through normally closed contacts RC5 (controlled by the coil Rc), normally closed contacts N1 of a current responsive relay having a coil N, and the normally closed push button switch S2. Thus, the relay coil Re remains energized and the motor continues to run in a direction to expand the-mandrel arms. j

1t will be observed that the relay coil N is connected directly in series with one of the supply lines forthe motor 95. The coil N is so designed as to be responsive only to current of a predetermined minimum value, so.

that as long as the motor 95 does not encounter a heavy load the contacts N1 remain closed. Whenever the mandrel arms reach their outer limit of travel or when they rmly engage the inner surface of a1 coil placed around the arms, a relatively heavy load will be imposed on the motor 95` and it will draw increased current. This increase in current is suicient to energize the coil N and thus toropen the contacts N1. Accordingly, the coil Reis deenergized and the contacts Re1 3'opened to automatically deenergize the motor 95. The normally closed contacts RC5 in series with the seal-in circuit for the relay coil Re insure that the latter coil may not remain energized when the Rc coil is subsequently energized. Additionally, the coil N is prevented from opening its normally closed contacts N1 as a result of the relatively great surge of starting current drawn by the motor 95 when ftheswitch S1` is initially depressed by the provision of"a second set of normally open contacts S11, for the latter `switch which `are connected directly in parallel with the coil N. Thus, during the short interval that the` motor 95 is being started, the coil N is shorted out by the contacts S11, and the normally closed contacts N1 remain closed so that the seal-in circuit becomes complete upon energization of the relay coil Re. I By the same token, contracting movement of the mandrel arms `is initiated by depressing another push button switch S3 thereby completing a circuit through the coil Rc, the contacts Saa of the push button switch,

and the normally closed contacts of the switch S2. This energizes the coil `Rc which closes the contacts Rc1 3 to` energize the motor 95 for rotation in the opposite direction. At the'same time, normally open contacts RC4, controlled by the coil Rc close to complete a seal-in circuit through the `latter coil, through the contacts Rar, through normally closed contacts Re5, through normally closed contacts M1 of a ,second current responsive relay having a coil `M, and through the normally closed push button switch S2. Accordingly, once contracting movement ofthe mandrel arms has been initiated by depressing the switch S3, the relay coil Rc is sealed-in and the motor 95 continues `to"run. lThe relay coil M is connected directly in series with one of the supply lines for the motori 95 and, as in the case of the relay coil N, is so designed as to be responsive only to current above a` predetermined minimum value drawn when the motor 95 is heavily loaded. Thus, when the mandrel arms 21 have been contracted into mutual `abutting engagement and the motor 95 is consequently loaded to draw a heavier` current, the coil M is energized to open the contacts M1.` This deenergizes the coil Rc and permits opening of the contacts Rc1 3, so that the motor 95 is automatically deenergized.` Itwill be observed that thel switch S3 includes a second set of normallyopen contacts S31, which are connected directly in parallel with the relay coil M. Thus, when the switch S3 is temporarily depressed as the motor` 95 is started in a contracting direction, the. coil M is shorted out andwill not be energized by the heavy starting current of the motor. The contacts M1, therefore, remained closed so that the seal-in circuit for theV coil R,s may be completed as described.

It willbe` evident from the foregoing that an operator may deenergize the motor at any time simply by depressing the push button switch S2. Further, provision is made for quickly reversing the direction of motor rotation, that is for plugging the motor to move the mandrel arms in the opposite direction from that in which they may be moving at any given time. For this purpose, a plugging switch` S4 of the single pole, double-throw type has oneof its contacts S41, connected through normally closed contacts Res of the relay coil Re to the common connection between the coil Re and the switch S1. The second contact S41J of the switch S4` is similarly connected through a normally closed contact Rcs to the common connection between the coil Rc and the switch S3. The common movable contact of the switch S4 is connected directly `to Athevoltage supply through the overload device O2. The operation of the plugging switch may therefore be described as follows. If the motor is initially energized by the relay coilRc so as to be driving the mandrel arms in a contracting direction, closure of thel switch S4 through the contact S4, energizes the coil Re; Thiscauses closure of the contacts R914 and opening of the `normally closed `contacts R85. The lattervthus breaksthe seal-in circuit of the relay Rc, deenergizing the sameand opening the contacts R1 3. Simultaneously, however, the seal-in circuit for the relay coil Re is completed so that the motor begins and continues to run inthe opposite direction to expand the mandrel arms. It will be noted that closure of the switch S4 to the contact S11, at the time when the relay coil Rc is energized produces no elec't whatever since such coil is already ener-` gized through its seal-in circuit. i

On the other hand, when the motor is initially running in a direction to expand the mandrel arms by virtue of the relay Re being sealedin, closure` of the switch S1 to the Contact S41, energizes the coil Rc. This closes the contacts R1 3.and opens the normally closed contacts RC5 to deenergize the relay coil Re. At the same time,` the normally open contacts RC4 are closed to complete the seal-in circuit for the coil Rc so that the motor is quickly reversed and continues to run in a direction 1 to contract the mandrel arms.` In either case, `when, a

predetermined resistance or load is placed on the motor` as a `result: of the mandrel arms` reaching one limit of their travellor contacting the inner` surface of acoil, either the relay M or the relay N operates to deenergize the sealed-in coil.Re or Re to thereby automatically deenergize the I no'tor 95. V i

, In order `to rotate a coil held on the mandrel 19 either for winding orunwinding the same, a power drivefor the `hollow shaft 18 `is provided. As `seen in Fig. 1, such drive may comprise a second motor 100 suitably mounted and connected,` as `by a V `belt 101 running over a pulley 102 fast on the shaft. a coil, a particular problem arises in connection with the need for the sheet material to have freedom to shift laterally,s`o that it, may be alined with the utilization machine being fed from the coil. For example, if the utilization machine, such as a slitter and recoiler, is allowed simply to pull or strip` the material from the coil with Vthe shaft `18 turning freely in its bearings, an"exc`essive tension may be developed in the web of material causing prohibitive stretching. Further, the tightness` of the coil tends to increase byvirtue ofsuch tension. This tightening of the coil prevents sidewise movement of the outer for smooth feeding into the utilization machine especially if the coilwas originally if the speed of the motor 100 is constant during the unwinding of the complete coil, the linealspeed of the material being unwound will decrease as the coil diam eter decreases. This is particularly objectionable where the utilization device is intended to accept the unwound material at auniform speed. It will be understood that theutilization device is power driven to take up material unwound from a coil; it is desirable, however, that the utilization device be free of the requirement of pulling or stripping the material from the coil.

In the fulfillment of one object of the invention, the

t above described diiiiculty is eliminated by choosing the speed of the motor to be such that even when the coil on the mandrel has a small diameter, the material is unwound faster than it is taken up by the utilization machine. `In addition, control apparatus is provided which isV operative to` deenergize and energize the motor in response respectively tothe presence or absence of a loose outer `loop of material depending a predetermined distance `below the coil. Thus, the coil is speeded up when the motor is energized so that a loose loop develops,

the motor then being deenergized until take-up by the utilization'device starts to consume the loop.`

" Such an automatic control arrangement for maintaitb" In the case of uuwinding` layer which may be necessary` wound unevenly.` Still further,

7 .ing ze .1905s loop of ,material lone :coil 'being unwound yis schematically exemplified :in Fig. 8. .As :there shown, @$95.1 .20 of .sheet materalis ycarried on .the mandrel .19 of a .coil 'holder Such as that illustrated in Fig. l. The coilis being unwound from the mandrel `and rewound on a power driven shaft 104 of. a utilization device. The speed of. the motor V100, when running, is .sucient t rotate the mandrel 19 fast enough to :unwind the .coil at a greater rate than v material is taken up by rotation of `theshaft 104. For controlling the motor 100, it is energized through contacts RM1 and Rm of a motor controlling relay having a coil RM, the RMIz contacts being in series with a suitable voltage source. The coil is controlled lin a manner such that the contacts RMLL are closed whenever a loose loop of material does not dependa predetermined distance below the .coil 20, while' they are automatically opened in response to the presence of such a loose loop.

This operation is achieved by connecting the coil RM across the voltage source in series with normally closed contacts Rm of a relay having a low voltage actuating coil RL., The latter ,coil is connected in series circuit with the low voltage secondary winding T2 of a transformer l having its primary winding T1 energized from the voltage source as indicated. Serially connected with the coil RL and secondary winding T2 are the coil holder support 15 and a conductive element or plate 1,05 disposed beneath the mandrel 19. It will be apparent that by employing the step down transformer T a very lowvoltage (in the order of 12 volts) is employed in the secondary circuit thereby eliminating the possibility of electrical shock or injury to workmen who might touch the support 15 and the plate 105.

Vhenever a loose l-oop of the sheet metal material of the coil 20 depends into contact with the conductive plate 105, the secondary circuit is completed and the relay coil RL is energized. This, in turn, opens the contactsRm, deenergizing the coil RM and opening the contacts Rum to thereby deenergize the motor 100. The take-up of the shaft 104 thus begins t-o consume the depending loop of the coil 20, and when such loopis lifted free of the plate 105, the coil RL is deenergized, the contacts Rm closed, the coil RM energized, and the contacts RMN closed to again energize the motor 100. The motor 100 thus runs until the depending loop again contacts the plate 105, whereupon the cycle of operation is repeated. It will be apparent, from the foregoing,

that this cycle of operation takes place relatively fast so -that a depending loop of approximatelyl uniformV length is continuously maintained, thereby permitting the shaft 104 to take up the material being unwound from the coil 20 as it may require.

Also illustrated in Fig. 8 is a normally open push button switch S5 connected in parallel with the contacts Rm for permitting manual initiation of energization for the motor 100. For stoppage, a normally closed push button switch S6 is connected in circuit with the relay coil RM in order that an operator may deenergize the motor 100 at any time during the operation described above.

Turning now to Figs. 9, 10 and l1, a modified embodiment of the invention is there illustrated, more particularly a modilied construction of the expanding mandrel which is susceptible of convenient power actuation by hydraulic means, By the provision of pressure regulating means for the hydraulic source, movement of the mandrel arms is terminated whenever resistance to such movement balances the force exerted by the hydraulic actuator.

As here illustrated, lthe modied yform of expanding mandrel comprises a, universal machine tool chuck ofl the crank type, having its jaws replaced with the special arms 21, previously described` with reference to Figs. 1 ,1 5 and 6,. Ille. chuck includes a hollow housing 110 having a collar 111 threaded on the end of the shaft 1.8. The outer face .of the housing has bolted `.to it three circularly spaced pairs of way members '112 slotted to receive radially slidable pads 114. For retention against circumferential movement with freedom for radial movement, the pads 114 have integral keys 115 riding in cooperatively spaced guide slots 116 (Fig. l0) of the way members. shaped to receive the butt ends of the special mandrel arms 21, as described above in connection with Fig. 4.

For adjusting the radial positions of the pads 114 in unison, they are provided with recesses 118 (Fig. 1l) receiving balled ends 119 Vof crank members 120 extending vthrough radial slots 121 in the outer face of the housing. The crank members are generally rightanglcd in form and pivoted on pins 122 carried by brackets 124 bolted within the housing. `The opposite balled ends 125 of the crank members extend into a circumferential groove 126 of a crank collar 128 which.

is mounted for free rotation of the end of the axially movable actuator rod 81 by a bronze bearing 129 and retained by a lock nut 130 and washer 131. The actuator rod 81 extends through the hollow shaft 1.8 as previously described in connection with Fig. l and is mounted for rotation relative to the latter by a pair of bearing sleeves 132. That is, the shaft 18, chuck housing 110, and crank collar 128 may all rotate freely as a unit while the actuator rod 81 remains stationary, the latter being axially movable to elfect pivoting of the crank members 120 and to thereby radially position the pads For shifting the actuator rod 81 axially to effect such radial adjustment of the pads 114 and arms 21, its right end may be connected (in lieu of the motor 95 in Fig. l) to the ram of a double-acting pneumatic or hydraulic cylinder (not shown). Since the crank collar 128 is journaled on the left end of the actuator rod 81, the latter need not turn with the shaft 18 as it rotates. A rotary pneumatic or hydraulic joint is, therefore, unnecessary and the rod 81 need be only mechanically coupled to the ram. By positioning the ram of the cylinder, therefore, to adjust the actuator rod 81 axially, the mandrel arms 21 may be expanded or retracted radially toengage or disengage the central opening of the coil. Such power adjustment may be accomplished in an instant with little or no effort. force exerted by the arms on one another when retracted, or on the inner surface `of a coil when expanded, may be controlled by means of a suitable pressure regulator (not shown) for the hydraulic cylinder.

ll claim as my invention:

l. A coil holder for strip metal comprising, in combination, a support, a shaft journaled in said support, an expanding mandrel on said shaft kand having a plurality of circularly spaced, axially extending arms, power means for radially expanding and retracting said arms, control means responsive to a predetermined resistance to radial movement of said arms for automatically deenergizing strip metal for deenergizing said drivingv means in re-V sponse to the presence of a slack loop depending a predetermined distance from the coil. 4

2. A coil holder for sheet metal comprising, in combination, a support, a shaft journaled on said support, a mandrel on said shaft having a plurality of circularly spaced, axially extending arms adapted for insertion intov the central opening of a coil of sheet metal, electric power means for radially expanding and contracting said arms in unison, control means operative uponmanual` initiation to energize said power means and automatically operative upon a predetermined resistance to. radial movement of said arms to deenergize said power means, electric driv- The `faces of the pads 114 areA The maximumr ing means `for rotating said shaft to unwind the coil faster than sheet metal is stripped from the coil, and a control circuit including as a part thereof a slack loop of the sheet metal depending from the coil for automatically energizing and deenergizing said driving means in response rcspectively to the absence or presence of a slack loop depending a predetermined distance beneath the coil to thereby maintain looseness in the outer layers of the coil affording freedom for lateral shifting of the same.

3. A coil holder comprising, in combination, a support, a shaft journaled on said support, an expanding mandrel on said shaft having a plurality of circularly spaced, axially extending arms adapted for insertion into the central opening of a coil of sheet metal to support the same, a mechanism for radially expanding and retracting said arms, a reversible electric motor for driving said mechanism, a control circuit for said motor including a current responsive relay in series with said motor and operative to deenergize the same in response t-o a current of predetermined magnitude drawn by said motor when said arms engage the inside of the coil or one another, a second motor for driving said shaft to unwind the coil faster than material is stripped therefrom, and a control circuit for said second motor including a conductive element disposed beneath said arms and a control relay connected in series between said frame and said element, said control relay being operative to deenergize said second motor when a slack loop from the coil contacts said element to complete the control relay circuit.

4. A coil holder comprising, in combination, a support; a hollow shaft journaled on said support; an expanding mandrel fixed on said shaft and including a universal machine tool chuck with the jaws thereof removed, a plurality of circularly spaced, elongated, axially extending arms fixed to said chuck in lieu of the jaws, and a mechanism in said chuck for radially expanding and contracting said arms in unison; an actuator shaft disposed within said hollow shaft and connected to operate said chuck mechanism, a iirst electric motor drivingly connected with said actuator shaft to radially adjust said arms; a current responsive relay in series with said rst motor and operative in response to current of a predetermined minimum value indicative of predetermined resistance to movement of said arms to automatically deenergize said first motor; a second motor for driving said hollow shaft to unwind a coil of conductive sheet material on said mandrel arms faster than material stripped from the coil; a conductive element beneath said mandrel arms; and a control circuit including said element, said support, and a control relay which is completed when a slack loop of the coil material engages said conductive element, and means including said control relay for automatically energizing and deenergizing said second motor in response respectively to the interruption and completion of said control circuit.

5. In a coil holder, the combination with a mandrel having radially expandible and retractable arms, of power means for radially moving said arms, and control means operative upon said power means for automatically deenergizing the latter in response to predetermined resistance to the movement of said arms, occasioned by the latter reaching the limits of their travel or engaging the inner surface of a coil.

6. In a coil holder, the combination with an expanding mandrel having a plurality of arms and a mechanism for relatively expanding and contracting said arms, of an electric motor for driving said mechanism, and a control circuit for said motor including means responsive to a predetermined resistance to the movement of said arms for automatically deenergizing said motor.

7. In a coil holder, the combination with an expanding4 mandrel having a plurality of arms and a mechanism for radially expanding and contracting said arms in unison, of a reversible electric motor for driving said mechanism, and an electric control circuit for said motor including means for manually initiating cnergization of said motor to expand and contract said arms, and a relay in circuit with said motor and responsive to current ow above a predetermined value for automatically deenergizing said motor.

8. In a coil holder, the combination of means for rotatably supporting a coil of sheet metal, with power means for rotationally driving said supporting means to unwind the coil, and means controlled by current conduction through and responsive to the length of a slack loop in the outer layer of the coil' for automatically deenergizing and energizing said power means to thereby maintain such outer layer loose with freedom to shift laterally.

9. In a coil holder, the combination of means for ro tatably supporting a c-oil of sheet metal, with an electric motor for rotationall'y driving the coil to unwind the same faster than material is stripped from it, and an electric control circuit for automatically energizing and deenergizing said motor in response to the absence or presence of a slack loop of metal depending a predetermined distance from the coil, said circuit including as a current conducting portion thereof the slack loop when the latter depends said predetermined distance, whereby the outer layer of said coil is maintained loose with freedom to shift laterally.

10. In a holder for rotatably supporting a coil of con` ductive sheet material, the combination of a journaled shaft, a mandrel on said shaft for supporting the coil, a motor for driving said shaft to unwind the coil, and a circuit for maintaining loose loops of the sheet material in order that it may be laterally shifted :as it is unwound from the coil, said circuit including a conductive plate disposed beneath the coil', and means electrically connected between said shaft and said plate for deenergizing said motor when a loose loop from the coil contacts said plate.

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